Boris Johnson will visit key European capitals this week in his first overseas trip since becoming UK prime minister, as fears of a potentially disastrous no-deal Brexit in October grow.
Government leaks published in The Sunday Times warned of significant disruptions to the supply of fresh food and medicine if the UK left the EU on October 31 without a divorce deal.
Economists and many MPs have said a no-deal departure could send the UK into a recession.
There are also fears that sharing law enforcement data and the health of the financial services industry could be damaged.
Mr Johnson’s predecessor, Theresa May, stepped down last month after the withdrawal agreement she had negotiated with Brussels was rejected three times by Parliament.
He wants to renegotiate an agreement with Brussels, but insists he will take Britain out of the EU on October 31 with or without a deal.
The EU has been united in saying the withdrawal deal cannot be reopened.
Downing Street said Mr Johnson will travel to Berlin on Wednesday for talks with German Chancellor Angela Merkel, and to Paris on Thursday for discussions with French President Emmanuel Macron.
A leader of the Eurosceptic movement, Mr Johnson has gained support from the right-wing factions of the ruling Conservative Party, which he leads.
But he has alienated the moderate elements, and opposition parties are likely to bring a confidence vote in Mr Johnson’s government when Parliament returns in September.